​@sanjay_novo 

Do we have any option for downloading all miro boards at once

This is currently no such option in Miro.

Wish List

I’d recommend adding this as an Idea in the Wish List category by following the guidelines here: Wish List: Everything You Need to Know.

If you do create a Wish List Idea post, I would also recommend that you post a link to it back here, so that future readers of this post can quickly get to and vote for your Idea.

Miro Developer Platform REST API

You could explore the REST API docs to see if you could build your own export/download feature:

https://developers.miro.com/reference/enterprise-create-board-export